WarriorFX

A lot of dieting strategies over recent years place less stress on fat and more on carbohydrate. Nutritional outlines by medical professionals have revealed the affect carbohydrates have on body composition and health; such as: The Zone, The Paleo Diet - the Atkin’s Diet set out to completely avoid them. Nutritional experts everywhere adopted a way to determine the quality of any carbohydrate-containing food using a Glycemic Index. The GI was introduced in 1981 to provide a ranking system for carbohydrates based on how they affect blood glucose levels. To this day, the GI usually compares, gram-for-gram, the impact of 50 grams of carbohydrate between varying foods. This is where critics rang in to dispute the usefulness of such data - introducing the Glycemic Load, comparing GI to actual portion sizes.

Based solely on GI, foods with a high rating may look problematic but the true effect on blood sugar control is marginal if carbohydrate intake is low, per serving. To illustrate this, white rice has a GI of 64, pretty high. However, eating a one-cup serving presents half the glucose response of a two-cup serving – portion relative to carbohydrate content needs to be addressed for real-world GI application.

As such, comparing different foods also presents a predicament. A one-cup serving of white rice is easily eaten. But substituting it for a food with a higher GI but lower carbohydrate content per serving would impose less of an overall load on blood sugar. For example, a watermelon has a GI of 72, while a milk chocolate candy bar tops out at only 43. Using only the GI, the candy bar appears superior in regulating blood glucose. However, when you take the GL into account, the candy bar is a much more concentrated source of carbohydrate than watermelon. You have to eat only three ounces of chocolate to get 50 grams of carbohydrate, whereas you would have to eat a very large watermelon to get 50 grams of carbohydrate.

A table comparing GI to GL was published by Harvard University in 1997, proposing a new scale to equalize the playing field and make real-world food comparisons possible. The July 2002 issue of The American Journal of Clinical Nutrition, provided a revised ranking system for food portions based on their GI and total carbohydrate content. To establish a load, the amount of carbohydrate, in grams, is multiplied by the food’s GI and then divided by 100. For example, a slice of watermelon has a GI of 72 but only five grams of carbohydrate. This gives this slice of watermelon a 3.6 rating for GL. The index might be high, but the load is low – due to the total carbohydrate content in a single serving.

Comparing GI to GL in common foods

Low GL and GI: All-bran cereal, Apples, Carrots, Chick peas, Grapes, Green peas, Kidney beans, Oranges, Peaches, Peanuts, Pears, Pinto beans, Red lentils, Strawberries, Sweet corn

Low GL and moderate GI: Beets, Cantaloupe, Pineapple, Sucrose (table sugar)

Low GL and high GI: Popcorn, Watermelon, Whole wheat flour bread, White wheat flour bread

Moderate GL and low GI: Apple juice, Bananas, Buckwheat, Fettucine, Navy beans, Orange juice, Parboiled rice, Pearled barley, Sourdough wheat bread

Moderate GL and GI: Life cereal, New potatoes, Sweet potatoes, Wild rice

Moderate GL and high GI: Cheerios, Shredded wheat

High GL and low GI: Linguine, Macaroni, Spaghetti

High GL and moderate GI: Couscous, White rice

High GL and high GI: Baked Russet potatoes, Cornflakes

International table of glycemic index and glycemic load values: 2002, American Journal of Clinical Nutrition, Vol. 76, No. 1, 5-56, 2002, American Society for Clinical Nutrition